Oil pressure supply device

ABSTRACT

An oil pressure supply device supplies, to an oil chamber, an oil pressure generated by suctioning oil from an oil source with an oil pump. The oil pressure supply device includes a first oil passage connected to a suction side of the oil pump; a first check valve provided in the first oil passage and configured to close the first oil passage and prevent oil from moving to the oil source side when the oil pump is stopped; a second oil passage connected to a discharge side of the oil pump; and a second check valve provided in the second oil passage and configured to close the second oil passage and prevent oil from moving to the oil pump side when the oil pump is stopped. When the oil pump is stopped, the second check valve closes the second oil passage earlier than the first check valve closes the first oil passage.

TECHNICAL FIELD

The present invention relates to an oil pressure supply device.

BACKGROUND ART

JP 2016-79992 A discloses an oil pressure supply device that supplies anoil pressure to an automatic transmission or the like. The oil pressuresupply device includes two pumps, that is, a mechanical oil pumpoperated by an engine and an electric oil pump operated by a motor. Theoil pressure supply device supplies an oil pressure by using themechanical oil pump and the electric oil pump in combination or byswitching between the mechanical oil pump and the electric oil pump inaccordance with a traveling condition of a vehicle.

SUMMARY OF INVENTION

The electric oil pump suctions oil from an oil reservoir formed in anoil pan via an oil passage. When the electric oil pump is stopped andthe suction of oil is stopped, the air that has entered through gapsbetween components or the air that has accumulated in a strainer thatfilters oil enters the oil passage, so that the oil leaks from the oilpassage. As a result, when the electric oil pump is operated again, theelectric oil pump may suction the air in the oil passage and idle untilthe air is discharged, which may result in delay of the discharge of theoil.

It is required to prevent air from entering the oil passage connectingthe electric oil pump and the oil reservoir and to improve theresponsiveness of the electric oil pump.

According to an aspect of the present invention, an oil pressure supplydevice for supplying, to an oil chamber, an oil pressure generated bysuctioning oil from an oil source with an oil pump, is provided.

The oil pressure supply device includes:

-   a first oil passage connected to a suction side of the oil pump;-   a first check valve provided in the first oil passage and configured    to close the first oil passage and prevent oil from moving to the    oil source side when the oil pump is stopped;-   a second oil passage connected to a discharge side of the oil pump;    and-   a second check valve provided in the second oil passage and    configured to close the second oil passage and prevent oil from    moving to the oil pump side when the oil pump is stopped.

When the oil pump is stopped, the second check valve closes the secondoil passage earlier than the first check valve closes the first oilpassage.

According to the above aspect, it is possible to prevent air fromentering the oil passage connecting the electric oil pump and the oilsource, and to improve the responsiveness of the electric oil pump.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram of a belt continuouslyvariable transmission.

FIG. 2 is a diagram schematically showing a configuration of an oilpressure supply device.

FIG. 3 is a diagram showing a specific configuration of a check valveprovided in an oil passage.

FIG. 4 is an enlarged view around the check valve in FIG. 3 .

FIG. 5 is a diagram showing a specific configuration of a check valveprovided in an oil passage.

FIG. 6 is a diagram showing an operation of the check valve during anoperation of an electric oil pump.

FIG. 7 is a diagram showing an operation of the check valve when theelectric oil pump is stopped.

FIG. 8 is a diagram showing a case where a check valve is not providedin an oil passage as a comparative example.

FIG. 9 is a timing chart relating to the operation of the check valveaccording to the embodiment.

FIG. 10 is a timing chart relating to the operation of the check valveaccording to a comparative example.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings.

FIG. 1 is a schematic configuration diagram of a belt continuouslyvariable transmission 1.

FIG. 2 is a diagram schematically showing a configuration of an oilpressure supply device 2.

As shown in FIG. 1 , the belt continuously variable transmission 1 for avehicle includes, as a transmission mechanism, a pair of pulleys, i.e.,a primary pulley P1 and a secondary pulley P2, and an endless belt Bwound around the pair of pulleys.

In the belt continuously variable transmission 1, a speed ratio ofrotation transmitted between the primary pulley P1 and the secondarypulley P2 is changed by changing winding radii of the belt B at theprimary pulley P1 and the secondary pulley P2.

The winding radii of the belt B at the primary pulley P1 and thesecondary pulley P2 are changed by regulating oil pressures supplied toan oil chamber R1 and an oil chamber R2 attached to the primary pulleyP1 and the secondary pulley P2, respectively.

The belt continuously variable transmission 1 includes the oil pressuresupply device 2. The oil pressure supply device 2 regulates, by apressure regulating circuit 70, the oil pressure generated by amechanical oil pump 3 and an electric oil pump 4, and supplies theregulated oil pressures to the oil chambers R1 and R2.

The mechanical oil pump 3 is an oil pump that is driven by rotationreceived from a vehicle drive source such as an engine. The mechanicaloil pump 3 is switched between an operation and a stop in conjunctionwith an operation and a stop of the vehicle drive source. The electricoil pump 4 is driven by rotation received from a motor installedseparately from the vehicle drive source. The operation and the stop ofthe electric oil pump 4 are switched by switching between the operationand the stop of the motor by a control device (not shown).

The electric oil pump 4 may be operated in place of the mechanical oilpump 3 when the mechanical oil pump 3 is stopped, for example, at thetime of idling stop of the vehicle. Alternatively, the electric oil pump4 may be operated in combination with the mechanical oil pump 3 when ahigh oil pressure is required due to a downshift of the beltcontinuously variable transmission 1 or the like.

As shown in FIG. 2 , the belt continuously variable transmission 1includes a transmission case 5 that houses a transmission mechanism, andan oil pan 6 that stores oil OL is provided at a lower portion of thetransmission case 5 in a vertical line VL direction. The oil pan 6covers a lower opening of the transmission case 5. An oil reservoir PLwhich is an oil source is formed in the oil pan 6, and the mechanicaloil pump 3 and the electric oil pump 4 suction the oil OL from the oilreservoir PL.

Due to layout restrictions, the transmission case 5 is inclined suchthat a front end side of the transmission case is positioned above arear end side of the transmission case in a front-rear direction of thevehicle. The oil pan 6 attached to the transmission case 5 is alsoinclined upward from a rear end side toward a front end side of the oilpan in the front-rear direction of the vehicle.

Inside the oil pan 6, a control valve body 7 is disposed in a state ofbeing fixed to the lower portion of the transmission case 5. Thepressure regulating circuit 70 (see FIG. 1 ) is built in the controlvalve body 7.

A strainer 8 is fixed to a lower portion of the control valve body 7.The strainer 8 includes a suction port 81 for the oil OL in a lowerportion thereof, and includes a filter F for filtering the oil OL in aninner portion thereof.

The mechanical oil pump 3 and the electric oil pump 4 are installed atan upper portion of the strainer 8 in the vertical line VL direction. InFIG. 2 , in order to make the positional relation easy to understand,the mechanical oil pump 3 and the electric oil pump 4 are schematicallyshown in a circular shape, and suction ports 31 and 41 shown in FIG. 2are schematically shown with only positions thereof.

The mechanical oil pump 3 and the electric oil pump 4 are connected tooil passages 21 and 22 (see FIG. 1 ) provided inside the control valvebody 7, respectively, and suction the oil OL stored in the oil pan 6 viathe strainer 8.

The mechanical oil pump 3 is disposed near a rear end of the strainer 8in the front-rear direction of the vehicle, and the electric oil pump 4is disposed near a front end of the strainer 8. The mechanical oil pump3 and the electric oil pump 4 are respectively provided along linesegments X1 and X2 parallel to each other, but since the mechanical oilpump 3 and the electric oil pump 4 are disposed at the upper portion ofthe strainer 8 disposed in an inclined manner, a straight line Laorthogonal to the line segments X1 and X2 is inclined at a predeterminedangle θ with respect to a horizontal line HL.

Due to this inclination, a lower portion of the mechanical oil pump 3disposed near the rear end of the upper portion of the strainer 8 ispositioned in the oil reservoir PL, and a lower portion of the electricoil pump 4 is positioned in air above a liquid surface of the oilreservoir PL.

As shown in FIG. 1 , the mechanical oil pump 3 and the electric oil pump4 are provided with the suction ports 31 and 41 for the oil OL,respectively, and the strainer 8 is provided with connection ports 82and 83. The suction ports 31 and 41 and the connection ports 82 and 83are connected to each other via the oil passages 21 and 22,respectively.

As shown in FIG. 2 , due to the inclination of the strainer 8, thesuction port 31 provided in the lower portion of the mechanical oil pump3 is positioned in the oil reservoir PL, and the suction port 41provided in the lower portion of the electric oil pump 4 is positionedin the air. Since FIG. 1 is a schematic diagram, the suction port 31 ofthe mechanical oil pump 3 is also shown above the oil reservoir PL forconvenience.

As shown in FIG. 1 , the oil passage 22 connecting the suction port 41of the electric oil pump 4 and the connection port 83 of the strainer 8is provided with a check valve 91 as a valve device that preventsbackflow of the oil OL in the oil passage 22 when the electric oil pump4 is stopped.

The oil OL suctioned by the mechanical oil pump 3 and the oil OLsuctioned by the electric oil pump 4 are supplied from discharge ports32 and 42 to the pressure regulating circuit 70 via oil passages 23 and24, respectively.

The oil passages 23 and 24 are provided with check valves 92 and 93,respectively. The check valve 92 is a valve device that preventsbackflow of the oil OL in the oil passage 23 when the mechanical oilpump 3 is stopped. The check valve 93 is a valve device that preventsbackflow of the oil OL in the oil passage 24 when the electric oil pump4 is stopped.

The detailed configuration and operation of the check valves 91, 92, and93 will be described later.

The pressure regulating circuit 70 includes solenoids those are formedinside the control valve body 7 (see FIG. 2 ) and those are driven bycommands (energization) of the control device (not shown), and pressureregulating valves those operate based on signal pressures generated bythe solenoids.

A first pressure regulating valve 71 regulates a line pressure based onthe oil pressure generated by the electric oil pump 4 by regulating adrain amount of the oil OL from the first pressure regulating valve 71.The first pressure regulating valve 71 also supplies a part of the oilOL into the transmission case 5 (see FIG. 2 ) as a lubricating oil thatlubricates components of the belt continuously variable transmission 1.

The line pressure regulated by the first pressure regulating valve 71 issupplied to a second pressure regulating valve 72, a primary pressureregulating valve 73, and a secondary pressure regulating valve 74.

The second pressure regulating valve 72 regulates a pilot pressure basedon the line pressure.

The pilot pressure regulated by the second pressure regulating valve 72is supplied to a solenoid 75 on a primary pulley P1 side and a solenoid76 on a secondary pulley P2 side.

The solenoids 75 and 76 are connected to the primary pressure regulatingvalve 73 and the secondary pressure regulating valve 74, respectively.The solenoids 75 and 76 are controlled by the control device (notshown), regulate the supplied pilot pressures to desired signalpressures, and supply the signal pressures to the primary pressureregulating valve 73 and the secondary pressure regulating valve 74.

The primary pressure regulating valve 73 and the secondary pressureregulating valve 74 regulate, according to the signal pressures, theline pressure supplied from the first pressure regulating valve 71 tooperating pressures, and supply the operating pressures to the oilchambers R1 and R2.

FIG. 3 is a diagram showing a specific configuration of the check valve93 provided in the oil passage 24.

FIG. 4 is an enlarged view around the check valve 93 in FIG. 3 .

In the following description, a direction in which the oil OL is fedfrom the oil reservoir PL to the pressure regulating circuit 70 by thesuction of the electric oil pump 4 is referred to as an oil feedingdirection. FIG. 3 shows an upstream side end portion 24 a of the oilpassage 24 in the oil feeding direction (hereinafter, simply referred toas an “upstream side end portion 24 a”), which is connected to thedischarge port 42 of the electric oil pump 4.

As shown in FIG. 3 , the oil passage 24 is mainly formed inside thecontrol valve body 7. The upstream side end portion 24 a extends fromthe transmission case 5 to a control valve body 7 side and is formedinside a wall portion 51 connected to the control valve body 7.

The control valve body 7 is provided with a cylindrical wall portion 77surrounding an outer periphery of the oil passage 24, and a distal endportion 511 of the wall portion 51 is fitted to an outer periphery of adistal end of the cylindrical wall portion 77. Thus, the innerperipheral side of the cylindrical wall portion 77 communicates with theinside of the wall portion 51. The oil passage 24 is connected to theinside of the control valve body 7 from the upstream side end portion 24a formed inside the wall portion 51.

In the wall portion 51, a circular opening portion 51 a thatcommunicates the discharge port 42 of the electric oil pump 4 with theupstream side end portion 24 a of the oil passage 24 is formed so as topenetrate the wall portion 51 in a thickness direction. The openingportion 51 a is provided such that an opening direction (a direction ofan axis X3 that passes through a center of the opening 51 a and that isorthogonal to an opening surface of the opening portion 51 a in FIG. 3 )is orthogonal to an axis Y direction along a direction in which the oilpassage 24 extends in the control valve body 7.

As shown in FIG. 4 , on an outer periphery of the opening portion 51 a,a cylindrical peripheral wall portion 54 surrounding the opening portion51 a at a predetermined interval is provided with an inner diameter D2larger than an opening diameter D1 of the opening portion 51 a. Insidethe peripheral wall portion 54, a cylindrical spacer 55 and a seal ring56 are provided such that an opening 55 a of the spacer 55 and anopening 56 a of the seal ring 56 are oriented along the openingdirection of the opening portion 51 a.

The seal ring 56 is positioned on the electric oil pump 4 side of thespacer 55, and is sandwiched between the spacer 55 and a wall portion 43surrounding the discharge port 42 of the electric oil pump 4.

An opening diameter D3 of the opening 55 a of the spacer 55 is smallerthan the opening diameter D1 of the opening portion 51 a and larger thanan opening diameter Dx of the discharge port 42 of the electric oil pump4, and an opening diameter of the opening 56 a of the seal ring 56 islarger than the opening diameter Dx of the discharge port 42.

The discharge port 42 of the electric oil pump 4, the opening 56 a ofthe seal ring 56, and the opening 55 a of the spacer 55 areconcentrically disposed on an extension of the opening portion 51 a (onthe axis X3), and the movement of the oil OL discharged from theelectric oil pump 4 into the oil passage 24 is not blocked by the spacer55 or the seal ring 56.

The check valve 93 is installed in the oil passage 24 on the oppositeside of the spacer 55 with the opening portion 51 a interposed betweenthe spacer 55 and the oil passage 24.

The check valve 93 is a so-called flapper valve, and includes a valvebody 94 that is movable forward and backward in the direction of theaxis X3, and a spring Sp that biases the valve body 94 toward theopening portion 51 a side in the direction of the axis X3.

The valve body 94 is made of, for example, an aluminum alloy, andincludes a disk-shaped valve portion 95 and a columnar shaft portion 96,which are integrally formed. The valve portion 95 is disposed such thatone end surface 95 a side faces the opening portion 51 a side. The shaftportion 96 is provided on the other end surface 95 b side of the valveportion 95, and extends in the direction of the axis X3.

The wall portion 51 is provided with a housing portion 513 for the checkvalve 93 at a position facing the opening portion 51 a. The housingportion 513 is open to the inside of a connection portion of the oilpassage 24 on the extension of the opening portion 51 a (on the axisX3), and houses the check valve 93 moved in a direction away from theopening portion 51 a.

The housing portion 513 is a space having an inner diameter slightlylarger than an outer diameter D4 of the valve portion 95 of the valvebody 94, and a support portion 53 for the valve body 94 is formed at acenter of a bottom portion 513 a of the housing portion 513 so as toprotrude toward the oil passage 24 (the electric oil pump 4).

In the support portion 53, a hole portion 530 into which the shaftportion 96 of the check valve 93 is inserted is provided so as to beopen on the oil passage 24 side, and the hole portion 530 extendslinearly along the axis X3 in the support portion 53 in a direction awayfrom the oil passage 24.

One end of the hole portion 530 on the opening portion 51 a side in thedirection of the axis X3 is an opening end 530 a. A bottom portion 530 bis formed at the other end of the hole portion 530, and the hole portion530 is closed.

The hole portion 530 extends to the inside of the wall portion 51 beyondthe inner diameter side of the support portion 53. The shaft portion 96of the check valve 93 is inserted into the hole portion 530 from theopening end 530 a.

As shown in FIG. 4 , a portion of the support portion 53 surrounding theopening end 530 a of the hole portion 530 is a valve seat portion 531.When a distal end 96 b of the shaft portion 96 moves to the bottomportion 530 b and the entire length of the shaft portion 96 is housed inthe hole portion 530, a step portion 951 formed at a center of the valveportion 95 abuts against the valve seat portion 531 surrounding theopening end 530 a of the hole portion 530.

The spring Sp is externally inserted and attached to an outer peripheryof the support portion 53. One end of the spring Sp is positioned in thedirection of the axis X3 on an inner peripheral surface of the oilpassage 24, and the other end of the spring Sp abuts against the otherend surface 95 b of the valve portion 95.

In the present embodiment, the spring Sp is compressed in the directionof the axis X3 in a state in which the valve portion 95 of the checkvalve 93 abuts against the end surface 55 b of the spacer 55.

Therefore, when the electric oil pump 4 is stopped, the valve portion 95is pressed against the end surface 55 b of the spacer 55 by a biasingforce of the spring Sp, and is held at a position where the openingportion 51 a is closed.

When the electric oil pump 4 is operated in this state, a pressing forceof the oil OL discharged from the electric oil pump 4 acts on the valveportion 95. Therefore, when the pressing force becomes larger than thebiasing force of the spring Sp, the valve portion 95 is pushed back in adirection away from the spacer 55 while compressing the spring Sp in thedirection of the axis X3 (see FIG. 4 ).

Thus, the valve portion 95 is pushed into the oil passage 24 to aposition where the step portion 951 on the other end surface 95 b sideabuts against the valve seat portion 531, and the opening portion 51 aclosed by the valve portion 95 is open.

Thus, the discharge port 42 of the electric oil pump 4 communicates withthe oil passage 24 in the wall portion 51, and thus the oil OLdischarged from the electric oil pump 4 is supplied into the oil passage24 of the control valve body 7 through the upstream side end portion 24a.

In this way, the check valve 93 provided in the oil passage 24 switchesbetween communication and block between the oil passage 24 and thedischarge port 42 of the electric oil pump 4 in accordance with theoperation and the stop of the electric oil pump 4.

The check valve 92 shown in FIG. 1 , which is provided in the oilpassage 23 connecting the mechanical oil pump 3 and the pressureregulating circuit 70, may also be a flapper valve having the sameconfiguration as the check valve 93. Although detailed description isomitted, the check valve 92 switches between communication and blockbetween the oil passage 23 and the discharge port 32 of the mechanicaloil pump 3 in accordance with the operation and the stop of themechanical oil pump 3.

FIG. 5 is a diagram showing a specific configuration of the check valve91 provided in the oil passage 22.

As shown in FIG. 5 , the check valve 91 is provided at an upstream sideend portion 22 a of the oil passage 22 in the oil feeding direction(hereinafter, simply referred to as an “upstream side end portion 22a”), which is connected to the connection port 83 of the strainer 8.

The upstream side end portion 22 a is provided with an opening portion22 b communicating with the connection port 83. The opening portion 22 bis formed in a separate plate 78 disposed inside the control valve body7. The connection port 83 protruding upward from the strainer 8 isfitted into the control valve body 7 and faces the opening portion 22 bprovided inside the control valve body 7.

An opening direction of the opening portion 22 b is disposed along anaxis X direction which is an opening direction of the connection port83, and the opening portion 22 b is positioned above the connection port83 in the vertical line VL direction (see FIG. 2 ). By the suction ofthe electric oil pump 4, the oil OL flows from below upwards in thegravity direction and flows through the connection port 83 and theopening portion 22 b, and is introduced into the oil passage 22.

The check valve 91 is a flapper valve having the same configuration asthe check valve 93, and includes a valve body 94 including the valveportion 95 and the shaft portion 96. The shaft portion 96 is slidablysupported in a hole portion 22 c formed inside the control valve body 7in which the oil passage 22 is formed. The hole portion 22 c is providedalong the axis X direction which is the opening direction of the openingportion 22 b, and a support portion 22 d is formed on an outer peripheryof the hole portion 22 c. The spring Sp for biasing the valve portion 95is externally inserted into the support portion 22 d.

While the electric oil pump 4 is stopped, the valve portion 95 ispressed against the opening portion 22 b by the biasing force of thespring Sp to close the opening portion 22 b. When the electric oil pump4 is operated, a negative pressure generated by the electric oil pump 4suctioning the oil OL is applied. When the negative pressure becomeslarger than the biasing force of the spring Sp, the valve portion 95 ofthe check valve 91 is displaced in a direction away from the openingportion 22 b, and the opening portion 22 b is open.

In this way, the check valve 91 opens and closes the opening portion 22b in accordance with the operation and the stop of the electric oil pump4, thereby switching between communication and block between the oilpassage 22 and the connection port 83 of the strainer 8.

Here, as shown in FIG. 1 , the check valve 92 provided on the dischargeport 32 side of the mechanical oil pump 3 and the check valve 93provided on the discharge port 42 side of the electric oil pump 4 arerequired to have pressure resistance because a high oil pressure, whichis an original pressure of the line pressure, is applied to the checkvalves 92 and 93. As described above, the check valves 92 and 93 may bevalve bodies 94 made of, for example, an aluminum alloy in order toimprove the pressure resistance.

On the other hand, the pressure applied to the check valve 91 providedon the suction port 41 side of the electric oil pump 4 during theoperation of the electric oil pump 4 is a negative pressure lower thanthe original pressure. Therefore, since the required pressure resistanceis lower than that of the check valves 92 and 93, for example, the valvebody 94 of the check valve 91 may be made of a resin.

Hereinafter, the operation of the check valves 91 and 93 during theoperation and the stop of the electric oil pump 4 in the oil pressuresupply device 2 according to the present embodiment will be described.

FIG. 6 is a diagram showing the operation of the check valves 91 and 93during the operation of the electric oil pump 4.

Here, a case where the electric oil pump 4 is operated in combinationwith the mechanical oil pump 3 will be described. In FIGS. 6 to 8 , theconfiguration around the check valve 93 is shown in a simplified manner.

For example, when a high oil pressure is required due to the downshiftor the like of the belt continuously variable transmission 1, theelectric oil pump 4 is operated to increase the oil pressure supplied bythe mechanical oil pump 3.

When the electric oil pump 4 is operated by the control device (notshown) and suction of the oil OL is started, as shown in FIG. 6 , thecheck valve 91 of the oil passage 22 receives a negative pressure and isdisplaced in a direction in which the opening portion 22 b is open,whereby the oil passage 22 communicates with the connection port 83 ofthe strainer 8. Thus, the oil OL in the oil reservoir PL filtered by thestrainer 8 flows through the oil passage 22 and is suctioned into theelectric oil pump 4.

When the electric oil pump 4 discharges the suctioned oil OL from thedischarge port 42, the check valve 93 of the oil passage 24 receives theoil pressure which is the original pressure of the line pressure, and isdisplaced in a direction in which the opening portion 51 a is open.Thus, the oil passage 24 communicates with the discharge port 42 of theelectric oil pump 4. The oil OL suctioned into the electric oil pump 4from the strainer 8 flows through the oil passage 24. The originalpressure of the line pressure generated by the suction of the electricoil pump 4 is supplied to the pressure regulating circuit 70 via the oilpassage 24.

The original pressure supplied by the electric oil pump 4 is regulatedtogether with an original pressure supplied by the mechanical oil pump 3in the pressure regulating circuit 70, and is supplied to the oilchambers R1 and R2.

FIG. 7 is a diagram showing the operation of the check valves 91 and 93when the electric oil pump 4 is stopped.

When a required amount of oil pressure is supplied to the oil chambersR1 and R2, the control device (not shown) stops the electric oil pump 4.

When the electric oil pump 4 is stopped, as shown in FIG. 7 , the oilpressure is not applied to the check valve 93 of the oil passage 24, sothat the check valve 93 is displaced, by the biasing force of the springSp, in a direction in which the opening portion 51 a is closed, andblocks the communication between the oil passage 24 and the dischargeport 42 of the electric oil pump 4.

Similarly, since the negative pressure of the electric oil pump 4 is notapplied to the check valve 91 of the oil passage 22, the check valve 91is displaced, by the biasing force of the spring Sp, in a direction inwhich the opening portion 22 b is closed, and blocks the communicationbetween the oil passage 22 and the connection port 83 of the strainer 8.

In this way, in the present embodiment, when the electric oil pump 4 isstopped, an upstream side and a downstream side of the electric oil pump4 are blocked by the check valves 91 and 93, respectively.

Hereinafter, the operation in the case where either or both of the checkvalves 91 and 93 are not provided will be described as comparativeexamples 1, 2, and 3. In order to distinguish from the presentembodiment, in the comparative examples 1, 2, and 3, the oil passages 22and 24 are replaced with oil passages 22A and 24A (see FIG. 8 ).

Comparative Example 1: Case Where Both of Check Valves 91 and 93 are NotProvided

When the electric oil pump 4 is stopped, the oil OL flows back to theelectric oil pump 4 side from the mechanical oil pump 3 or the pressureregulating circuit 70 via the oil passage 24A. This backflow reduces theamount of the oil OL supplied from the mechanical oil pump 3 to thepressure regulating circuit 70. Thus, it is necessary to increase adischarge amount of the mechanical oil pump 3, which affects fuelconsumption in the vehicle.

Comparative Example 2: Case Where Check Valve 91 Is Not Provided

FIG. 8 is a diagram showing the comparative example 2.

Unlike the comparative example 1, since the check valve 93 is providedin the oil passage 24A, it is possible to prevent the backflow from themechanical oil pump 3 to the electric oil pump 4. On the other hand,when the suction of the oil OL by the electric oil pump 4 is stopped inthe oil passage 22A, air enters the oil passage 22A from gaps betweencomponents such as the suction port 41 of the electric oil pump 4positioned in the air. The air accumulated in the strainer 8 may enterthe inside of the oil passage 22A.

In this way, when air enters the oil passage 22A in which the checkvalve 91 is not provided, the oil OL leaks from the oil passage 22A.

When the electric oil pump 4 is operated in a state in which the oil OLis leaked from the oil passage 22A, the electric oil pump 4 may suctionthe air that first enters the oil passage 22A and may idle, and thetiming at which the discharge of the oil OL is started may be delayed.

Comparative Example 3: Case Where Check Valve 93 Is Not Provided

By providing the check valve 91 in the oil passage 22A, it is possibleto prevent the oil from leaking from the oil passage 22A. However, asdescribed above, the oil OL flows back from the mechanical oil pump 3 orthe pressure regulating circuit 70 to the electric oil pump 4 side viathe oil passage 24A in which the check valve 93 is not provided. Thecheck valve 91 is normally operated by the negative pressure generatedby the suction of the electric oil pump 4, and is not required to havepressure resistance. However, when a high pressure is applied to thevalve body 94 due to the backflow of the oil OL, the product life of thecheck valve 91 may be shortened.

As described above, in the case where the electric oil pump 4 is used incombination with the mechanical oil pump 3 at the time of a downshift orthe like in which a high oil pressure is required, it is required toquickly supply the oil pressure to the oil chambers R1 and R2.

Therefore, as shown in FIG. 7 , in the present embodiment, by providingthe check valve 91 in the oil passage 22, the oil OL is prevented fromleaking from the oil passages 22 and 24 when the electric oil pump 4 isstopped. Since the oil OL is held in the oil passages 22 and 24, theamount of air entering the oil passages 22 and 24 through the suctionport 41 and the discharge port 42 of the electric oil pump 4 is reduced.

As shown in FIG. 6 , when the electric oil pump 4 is operated in a statein which the oil OL is present in the oil passage 22, the idling due tothe suction of air is reduced. Further, since the electric oil pump 4suctions the oil OL in the oil passage 22 and starts to discharge theoil OL before the check valve 91 of the oil passage 22 is open, theelectric oil pump 4 promptly supplies the oil pressure to the oilchambers R1 and R2.

Further, as shown in FIG. 2 , the electric oil pump 4 suctions the oilOL stored in the oil reservoir PL. The oil OL is oil which is stirred inthe oil reservoir PL by the rotation of the components of the beltcontinuously variable transmission 1 and then falls into the oil pan 6along a wall surface of the transmission case 5 or the like. Therefore,the oil OL in the oil reservoir PL contains a large amount of airparticles K. The oil OL containing the air particles K is suctioned intothe strainer 8. The air particles K move upward in the vertical line VLdirection inside the strainer 8 due to buoyancy, and form an airreservoir Air.

As described above, in the strainer 8, the front end side where theelectric oil pump 4 is disposed is positioned above the rear end sidewhere the mechanical oil pump 3 is disposed in the vertical line VLdirection. Therefore, the air reservoir Air is easily formed on thefront end side of the strainer 8 where the electric oil pump 4 isdisposed.

In the case where the check valve 91 is not provided in the oil passage22, when the electric oil pump 4 is stopped, the air in the airreservoir Air formed on the front end side of the strainer 8 may enterthe oil passage 22 through the connection port 83 (see FIG. 1 ) due tothe suction of the oil OL by the mechanical oil pump 3. Accordingly, alarge amount of air may be suctioned when the electric oil pump 4 isoperated, and the discharge timing may be delayed.

In the present embodiment, when the electric oil pump 4 is stopped, thecheck valve 91 blocks the communication between the oil passage 22 andthe connection port 83 of the strainer 8, whereby when the electric oilpump 4 is stopped, the air accumulated on the front end side of thestrainer 8 can be prevented from entering the oil passage 22 through theconnection port 83 and the oil OL can be prevented from leaking from theoil passage 22.

When the electric oil pump 4 is operated, since the electric oil pump 4suctions the oil OL inside the oil passage 22 and starts to dischargethe oil OL, it is unlikely to lead to a discharge delay of the electricoil pump 4 even when the air in the air reservoir Air is suctioned afterthe check valve 91 is retracted to cause the oil passage 22 and theconnection port 83 to communicate with each other.

Further, in the present embodiment, by providing the check valve 93 inthe oil passage 24 as well, when the electric oil pump 4 is stopped, itis possible to prevent the oil OL from flowing back to the electric oilpump 4 side from the mechanical oil pump 3 or the pressure regulatingcircuit 70. This prevents a reduction in the amount of the oil OLsupplied from the mechanical oil pump 3 to the pressure regulatingcircuit 70, and further prevents a high pressure from being applied tothe check valve 91 of the oil passage 22 by the backflow of the oil OL.

In the present embodiment, a high pressure is also prevented from beingapplied to the check valve 91 by controlling the timing of the operationof the check valves 91 and 93.

FIG. 9 is a timing chart relating to the operation of the check valves91 and 93 according to the present embodiment.

FIG. 9 shows displacements of the check valve 91 and the check valve 93in accordance with the operation and the stop of the electric oil pump4. The graphs for the check valve 91 and the check valve 93 showdisplacement amounts thereof in the opening direction of the oilpassages 22 and 24, respectively, and when the displacement amounts arezero, the check valve 91 and the check valve 93 close the oil passage 22and the oil passage 24, respectively.

As shown in FIG. 9 , when the control device (not shown) outputs an ONsignal, the electric oil pump 4 is operated.

When the electric oil pump 4 starts to suction the oil OL in the oilpassage 22, a negative pressure is applied to the check valve 91, andthe check valve 91 starts to be displaced in a direction in which theoil passage 22 is open.

When the electric oil pump 4 starts to discharge the oil OL, an oilpressure is applied to the check valve 93, and the check valve 93 startsto be displaced in a direction in which the oil passage 24 is open.

The oil pressure of the electric oil pump 4 rapidly increases after theoperation is started, but after the oil passages 22 and 24 are open, thedischarge at an original pressure necessary for regulating the linepressure is maintained.

When the control device (not shown) outputs an OFF signal, the electricoil pump 4 stops the suction of the oil OL (timing T0). The oil pressureof the electric oil pump 4 starts to gradually decrease at a timing T1after the electric oil pump 4 is stopped, and becomes zero at a timingT2.

Since a flow rate of the oil OL in the oil passage 24 and the oilpassage 22 is reduced by stopping the suction and the discharge of theelectric oil pump 4, the oil pressure applied to the check valve 93 andthe negative pressure applied to the check valve 91 are graduallyreduced. Thus, at the timing T0 the check valve 93 and the check valve91 start to be displaced in directions in which the oil passages 22 and24 are closed, respectively.

The check valve 93 completes the closing of the oil passage 24 after theelapse of a time Ta from the timing T0, and the check valve 91 completesthe closing of the oil passage 22 after the elapse of a time Tb from thetiming T0. In the present embodiment, the time Ta is shorter than thetime Tb. That is, although the check valve 93 and the check valve 91start to be displaced at the same timing T0, the check valve 93 closesthe oil passage 24 earlier than the check valve 91 closes the oilpassage 22.

For example, a stroke speed of the check valve 93 is set to be fasterthan a stroke speed of the check valve 91 such that the check valve 93completes closing earlier than the check valve 91. The stroke speed maybe set by, for example, performing a test or simulation in advance andadjusting a load of the spring Sp constituting each of the check valves93 and 91.

The timing chart in FIG. 9 is merely an example. The check valve 93completes closing at least before the check valve 91, and the checkvalve 91 and the check valve 93 may not necessarily start to bedisplaced at the same timing.

FIG. 10 is a timing chart relating to the operation of the check valves91 and 93 according to a comparative example.

As shown in FIG. 10 , in the comparative example, the time Ta for thecheck valve 93 to close the oil passage 24 is longer than the time Tbfor the check valve 91 to close the oil passage 22. That is, before thecheck valve 93 completes the closing of the oil passage 24, the checkvalve 91 completes the closing of the oil passage 22.

The timing at which the check valve 91 completes the closing of the oilpassage 22 is before the timing T2 at which the oil pressure of theelectric oil pump 4 becomes zero, that is, a state in which the oilpressure of the electric oil pump 4 is still generated.

In this state, when the check valve 91 is closed before the check valve93, a part of the oil OL in the oil passage 24 may flow back to the oilpassage 22 on the upstream side in the oil feeding direction, and theoil pressure of the oil OL may be applied to the check valve 91 that isclosing the oil passage 22. The oil pressure of the backflow oil OL isincreased to the original pressure necessary for regulating the linepressure by the suction of the electric oil pump 4.

Meanwhile, as described above, since the check valve 91 of the oilpassage 22 is normally operated by a negative pressure generated by thesuction of the electric oil pump 4 and is not required to have pressureresistance as compared with the check valve 93, for example, a valvebody 94 made of a resin may be used.

However, when a high pressure is applied to the valve body 94 made of aresin due to the backflow of the oil OL, the product life of the checkvalve 91 may be shortened. In order to improve the pressure resistanceof the check valve 91, for example, a valve body 94 made of an aluminumalloy may be used, but a production cost of the check valve 91 mayincrease.

Further, the check valve 91 is pressed against the opening portion 22 b(see FIG. 5 ) of the oil passage 22 communicating with the connectionport 83 of the strainer 8. Therefore, the oil pressure applied to thevalve body 94 is also transmitted to the connection port 83, which maylead to a decrease in the product life of the strainer 8.

Therefore, in the present embodiment, as shown in FIG. 9 , by adjustingthe load of the spring Sp constituting each of the check valves 91 and93, the check valve 93 is set to complete the closing of the oil passage24 earlier than the check valve 91 completes the closing of the oilpassage 22.

Thus, since it is possible to prevent a part of the oil OL in the oilpassage 24 from flowing back to the oil passage 22 and a high pressurefrom being applied to the check valve 91, the possibility of a decreasein the product life can be lowered when the valve body 94 made of aresin, for example, is used as the check valve 91.

As described above,

-   (1) The oil pressure supply device 2 according to the present    embodiment supplies-   an oil pressure generated by suctioning the oil OL from the oil    reservoir PL (oil source) by the electric oil pump 4 (oil pump) to    the oil chambers R1 and R2.

The oil pressure supply device 2 includes: the oil passage 22 (first oilpassage) connected to the suction side of the electric oil pump 4;

-   the check valve 91 (first check valve) provided in the oil passage    22 and configured to close the oil passage 22 and prevent the oil OL    from moving to the oil reservoir PL side when the electric oil pump    4 is stopped;-   the oil passage 24 (second oil passage) connected to a discharge    side of the electric oil pump 4; and-   the check valve 93 (second check valve) provided in the oil passage    24 and configured to close the oil passage 24 and prevent the oil OL    from moving to the electric oil pump 4 side when the electric oil    pump 4 is stopped, in which-   when the electric oil pump 4 is stopped, the check valve 93 closes    the oil passage 24 earlier than the check valve 91 closes the oil    passage 22.

When the electric oil pump 4 is stopped, air may enter the oil passage22 through gaps or the like between components, and the air may causethe oil OL to leak from the oil passage 22 connecting the oil reservoirPL and the electric oil pump 4. When the oil OL leaks from the oilpassage 22, if the electric oil pump 4 is operated again, the electricoil pump 4 idles until the air is discharged, and the discharge of theoil OL may be delayed.

When the electric oil pump 4 is used during the stop of the mechanicaloil pump 3, such as idling stop, a slight operation delay does not causea problem. On the other hand, in the case where the electric oil pump 4is used as an auxiliary for the mechanical oil pump 3 when a high oilpressure is required, for example, when a continuously variabletransmission is downshifted, the electric oil pump 4 is required tooperate promptly.

Therefore, the check valve 91 that closes the oil passage 22 and thecheck valve 93 that closes the oil passage 24 when the electric oil pump4 is stopped are provided in the oil passages 22 and 24 respectivelyconnected to the suction side and the discharge side of the electric oilpump 4. Thus, it is possible to prevent the oil OL from leaking from theoil passage 22 when the electric oil pump 4 is stopped, and it ispossible to improve the responsiveness of the electric oil pump 4.

Here, when the check valve 91 on the suction side of the electric oilpump 4 is closed earlier than the check valve 93 on the discharge side,the oil OL in the oil passage 24 may flow back to the check valve 91,and a high pressure on the discharge side of the electric oil pump 4 maybe applied to the check valve 91, which may lead to a decrease in theproduct life. The valve body 94 of the check valve 91 may be made of analuminum alloy to improve the pressure resistance, but the productioncost increases.

In the present embodiment, when the electric oil pump 4 is stopped, byclosing the check valve 93 earlier than the check valve 91, it ispossible to prevent the oil OL in the oil passage 24 from flowing backto the oil passage 22 and a high pressure from being applied to thecheck valve 91, and it is possible to improve the responsiveness of theelectric oil pump 4 while preventing an increase in the production cost.

(2) The check valve 91 is a flapper valve that includes the valve body94 (first valve body) and the spring Sp (first spring member). The valvebody 94 is movable forward and backward in the opening direction (axis Xdirection) of the opening portion 22 b of the oil passage 22 and opensand closes the opening portion 22 b, and the spring Sp biases the valvebody 94 in a direction in which the opening portion 22 b is closed.

When the electric oil pump 4 is stopped, the valve body 94 is held, by abiasing force of the spring Sp, at a position at which the openingportion 22 b is closed, and when a negative pressure is supplied by theoperation of the electric oil pump 4, the valve body 94 is displaced ina direction in which the opening portion 22 b is open.

By using a flapper valve as the check valve 91, it is possible toincrease a flow rate of the oil OL when the oil passage 22 is open ascompared with, for example, a ball valve.

(3) The check valve 93 is a flapper valve that includes the valve body94 (second valve body) and the spring Sp (second spring member). Thevalve body 94 is movable forward and backward in the opening direction(axis X3 direction) of the opening portion 51 a of the oil passage 24and opens and closes the opening portion 51 a, and the spring Sp biasesthe valve body 94 in a direction in which the opening portion 51 a isclosed.

When the electric oil pump 4 is stopped, the valve body 94 is held, by abiasing force of the spring Sp, at a position at which the openingportion 51 a is closed by the valve body 94, and when an oil pressure issupplied by the operation of the electric oil pump 4, the valve body 94is displaced in a direction in which the opening portion 51 a is open.

By using a flapper valve as the check valve 93, it is possible toincrease the flow rate of the oil OL when the oil passage 24 is open ascompared with, for example, a ball valve.

(4) When the electric oil pump 4 is stopped, the loads of the springs Spof the check valve 91 and the check valve 93 are set such that the valvebody 94 of the check valve 93 closes the opening portion 51 a of the oilpassage 24 earlier than the valve body 94 of the check valve 91 closesthe opening portion 22 b of the oil passage 22.

Since the load of the spring Sp can be easily changed, an electroniccircuit or the like is not required, and the check valve 93 can beeasily controlled to be closed earlier than the check valve 91.

(5) The valve body 94 of the check valve 91 is made of a resin, and thevalve body 94 of the check valve 93 is made of an aluminum alloy.

Since the pressure resistance of the check valve 91 made of a resin islower than that of the check valve 93 made of an aluminum alloy, it ispossible to prevent a high pressure from being applied to the checkvalve 91 by closing the check valve 93 earlier than the check valve 91.

(6) The electric oil pump 4 suctions the oil OL from the oil reservoirPL, which is an oil source, via the strainer 8 that filters the oil OL,

-   the strainer 8 includes the connection port 83 with the oil passage    22, and-   the check valve 91 blocks the communication between the oil passage    22 and the connection port 83 when the electric oil pump 4 is    stopped.

When a high pressure is applied to the check valve 91 that closes theopening portion 22 b of the oil passage 22 communicating with theconnection port 83 of the strainer 8, the pressure is also transmittedto the connection port 83, which may lead to a decrease in the productlife of the strainer 8. In the present embodiment, when the electric oilpump 4 is stopped, the check valve 93 is closed earlier than the checkvalve 91, whereby the pressure can be prevented from being transmittedto the connection port 83.

While the embodiments of the present invention have been describedabove, the above description of the embodiments of the invention ismerely one example of application of the invention, and is not intendedto limit the technical scope of the invention to the specificconfiguration of the above embodiments.

In the present embodiment, as shown in FIG. 2 , an example in which thetransmission case 5 is disposed to be inclined due to layoutrestrictions or the like has been described, but the present inventionis not limited thereto. For example, if the layout is relatively free,the transmission case 5, the oil pan 6, and the strainer 8 may behorizontally disposed without being inclined, and the suction port 41 ofthe electric oil pump 4 may be positioned in the oil in the oilreservoir PL.

The present application claims a priority of Japanese Patent ApplicationNo. 2019-238015 filed with the Japan Patent Office on Dec. 27, 2019, allthe contents of which are hereby incorporated by reference.

1. An oil pressure supply device for supplying, to an oil chamber, anoil pressure generated by suctioning oil from an oil source with an oilpump, the oil pressure supply device comprising: a first oil passageconnected to a suction side of the oil pump; a first check valveprovided in the first oil passage and configured to close the first oilpassage and prevent oil from moving to the oil source side when the oilpump is stopped; a second oil passage connected to a discharge side ofthe oil pump; and a second check valve provided in the second oilpassage and configured to close the second oil passage and prevent oilfrom moving to the oil pump side when the oil pump is stopped, whereinwhen the oil pump is stopped, the second check valve closes the secondoil passage earlier than the first check valve closes the first oilpassage.
 2. The oil pressure supply device according to claim 1, whereinthe first check valve is a flapper valve that includes a first valvebody and a first spring member, the first valve body being movableforward and backward in an opening direction of an opening portion ofthe first oil passage and being configured to open and close the openingportion of the first oil passage, and the first spring member beingconfigured to bias the first valve body in a direction in which theopening portion of the first oil passage is closed, and the first valvebody is held, by a biasing force of the first spring member, at aposition at which the opening portion of the first oil passage is closedwhen the oil pump is stopped, and is displaced in a direction in whichthe opening portion of the first oil passage is open when a negativepressure is supplied by an operation of the oil pump.
 3. The oilpressure supply device according to claim 2, wherein the second checkvalve is a flapper valve that includes a second valve body and a secondspring member, the second valve body being movable forward and backwardin an opening direction of an opening portion of the second oil passageand being configured to open and close the opening portion of the secondoil passage, and the second spring member being configured to bias thesecond valve body in a direction in which the opening portion of thesecond oil passage is closed, and the second valve body is held, by abiasing force of the second spring member, at a position at which theopening portion of the second oil passage is closed when the oil pump isstopped, and is displaced in a direction in which the opening portion ofthe second oil passage is open when an oil pressure is supplied by theoperation of the oil pump.
 4. The oil pressure supply device accordingto claim 3, wherein when the oil pump is stopped, loads of the firstspring member and the second spring member are set such that the secondvalve body closes the opening portion of the second oil passage earlierthan the first valve body closes the opening portion of the first oilpassage.
 5. The oil pressure supply device according to claim 3, whereinthe first valve body is made of a resin, and the second valve body ismade of an aluminum alloy.
 6. The oil pressure supply device accordingto claim 1, wherein the oil pump suctions oil from an oil reservoir,serving as the oil source, via a strainer that filters the oil, thestrainer includes a connection port with the first oil passage, and thefirst check valve blocks communication between the first oil passage andthe connection port when the oil pump is stopped.